MAX7427CPA+

Overview

The MAX7427CPA+ is a 5th-order, lowpass, elliptic switched-capacitor filter designed for single-supply operation at +3V. It provides sharp rolloff with a transition ratio of 1.25 and typically 37dB of stopband rejection. The device supports clock-tunable corner frequencies ranging from 1Hz to 12kHz via a fixed 100:1 clock-to-corner frequency ratio. Operating supply current is 0.8mA, which reduces to 0.2µA in shutdown mode. Key electrical characteristics include -79dB THD + Noise, ±4mV output offset voltage, and a maximum capacitive load capability of 500pF at the output.

Feature Summary

• Elliptic lowpass filter topology providing steep rolloff and high stopband rejection
• Clock-tunable corner frequency adjustable between 1Hz and 12kHz
• Low-power operation with dedicated shutdown mode reducing current to microampere levels
• Internal oscillator or external clock input options for precise frequency control

Applications

• ADC anti-aliasing filtering
• Post-DAC signal reconstruction
• Speech processing systems
• CT2 base station receivers

Procurement Notes

Verify the specific suffix 'CPA+' against the manufacturer's official ordering guide to confirm the package type (Plastic DIP) and temperature range (0°C to +70°C). Ensure compatibility with single +3V supply requirements and check for lead-free compliance status if required by local regulations. Confirm availability through authorized distributors as stock levels vary.

Selection Notes

Select the MAX7427 over the MAX7426 when a +3V single supply is available, as the MAX7426 requires +5V. Both devices share identical filter characteristics and pinouts. Consider the internal oscillator versus external clock requirement based on the need for tight cutoff-frequency control versus design simplicity. Verify that the application can tolerate the 100:1 clock-to-corner ratio constraint.

Part Context

The MAX7427 belongs to the MAX7426/MAX7427 family of 5th-order elliptic switched-capacitor filters manufactured by Analog Devices/Maxim Integrated. These devices utilize a passive ladder emulation technique using switched-capacitor integrators to achieve low component sensitivity compared to cascaded biquadratic designs. The family is optimized for low-noise, low-distortion applications in portable and battery-powered systems.

Replacement Considerations

The MAX7426 is the primary functional substitute within the same family, differing only in the required supply voltage (+5V vs. +3V). Other Maxim SCF families like the MAX291/MAX292 series may serve similar roles but require different supply configurations and offer varying order specifications.